This invention relates to the method of using neurotrophic cyclophilin inhibitor compounds having an affinity for cyclophilin immunophilins as inhibitors of the enzyme activity associated with immunophilin proteins, and particularly inhibitors of peptidyl-prolyl isomerase or rotamase enzyme activity of the cyclophilins.
The term immunophilin refers to a number of proteins that serve as receptors for the principal immunosuppressant drugs, cyclosporin A (CsA), FK506, and rapamycin. Known classes of immunophilins are cyclophilins, and FK506 binding proteins, such as FKBP. Cyclosporin A binds to cyclophilin while FK506 and rapamycin bind to FKBP. These immunophilin-drug complexes interface with a variety of intracellular signal transduction systems, especially in the immune system and the nervous system.
Immunophilins are known to have peptidyl-prolyl isomerase (PPIase) or rotamase enzyme activity. It has been determined that rotamase activity has a role in the catalyzation of the interconversion of the cis and trans isomer of immunophilin proteins.
Immunophilins were originally discovered and studied in immune tissue. It was initially postulated by those skilled in the art that inhibition of the immunophilins rotamase activity leads to the inhibition of T-cell proliferation, thereby causing the immunosuppressive action exhibited by immunosuppressive drugs such as cyclosporin A, FK506, and rapamycin. Further study has shown that the inhibition of rotamase activity, in and of itself, is not sufficient for immunosuppressant activity. Instead immunosuppression appears to stem from the formulation of a complex of immunosuppressant drugs and immunophilins. It has been shown that the immunophilin-drug complexes interact with ternary protein targets as their mode of action. In the case of FKBP-FK506 and FKBP-CsA, the drug-immunophilin complexes bind to the enzyme calcineurin, inhibiting T-cell receptor signalling leading to T-cell proliferation. Similarly, the complex of rapamycin and FKBP interacts with the RAFT1/FRAP protein and inhibits signalling from the IL-2 receptor.
Immunophilins have been found to be present at high concentrations in the central nervous system. Immunophilins are enriched 10-50 times more in the central nervous system than in the immune system. Within neural tissues, immunophilins appear to influence nitric oxide synthesis, neurotransmitter release, and neuronal process extension.
Surprisingly, it has been found that picomolar concentrations of an immunosuppressant such as cyclosporin A stimulates neurite out growth in PC12 cells and sensory neurons, namely dorsal root ganglion cells (DRGS). More particularly, it has been found that drugs with a high affinity for cyclophilin are potent rotamase inhibitors and exhibit excellent neurotrophic effects. Snyder et al., xe2x80x9cImmunophilins and the Nervous Systemxe2x80x9d, Nature Medicine, Volume 1, No. 1, Jan. 1995, 32-37. These findings suggest the use of inhibitors of cyclophilin rotamase activity in treating various peripheral neuropathies and enhancing neuronal regrowth in the central nervous system (CNS). Studies have demonstrated that neurodegenerative disorders such as Alzheimer""s disease and Parkinson""s disease may occur due to the loss, or decreased availability, of a neurotrophic substance specific for a particular population of neurons affected in the disorder.
Several neurotrophic factors effecting specific neuronal populations in the central nervous system have been identified. For example, it has been hypothesized that Alzheimer""s disease results from a decrease or loss of nerve growth factor (NGF) . It has thus been proposed to treat SDAT patients with exogenous nerve growth factor or other neurotrophic proteins such as brain derived growth factor, glial derived growth factor, ciliary neurotrophic factor, and neurotropin-3 to increase the survival of degenerating neuronal populations.
Clinical application of these proteins in various neurological disease states is hampered by difficulties in the delivery and bioavailability of large proteins to nervous system targets. By contrast, immunosuppressant drugs with neurotrophic activity are relatively small and display excellent bioavailability and specificity. However, when administered chronically, immunosuppressants exhibit a number of potentiially serious side effects including nephrotoxicity, such as impairment of glomerular filtration and irreversible interstitial fibrosis (Kopp et al., 1991, J. Am. Soc. Nephrol. 1:162); neurological deficits, such as involuntary tremors, or non-specific cerebral angina such as non-localized headaches (De Groen et al., 1987, N. Engl. J. Med. 317:861); and vascular hypertension with complications resulting therefrom (Kahan et al., 1989 N. Engl. J. Med. 321: 1725).
The present invention provides both immunosuppressive and non-immunosuppressive cyclophilin inhibitor compounds containing small molecule cyclophilin rotamase inhibitors which are extremely potent in augmenting neurite outgrowth, and for promoting and stimulating neuronal growth and regeneration in various neuropathological situations where neuronal repair can be facilitated. These situations include augmenting neurite outgrowth and promoting neuronal growth and regeneration for nerve damage by physical injury or disease state such as diabetes, including peripheral nerve damage, damage to motor neurons, damage to the central nervous system (spinal cord and brain) including damage to spinal neurons and neurons in the brain, brain damage associated with stroke, and for the treatment of neurological disorders relating to neurodegeneration, including Parkinson""s disease and Alzheimer""s disease.
This invention relates to the method of using. neurotrophic cyclophilin inhibitor compounds having an affinity for cyclophilin-type immunophilins as inhibitors of the enzyme activity associated with immunophilin proteins, and particularly inhibitors of peptidyl-prolyl isomerase or rotamase enzyme activity.
A preferred embodiment of this invention is a method of treating a neurological activity in an animal, comprising:
administering to an animal an effective amount of an immunosuppressive cyclosporin represented by formula I and pharmaceutically acceptable salts thereof, wherein:
R1 is MeBmt or [3-DesoxyMeBmt] or represented by formula III; wherein positions 2, 3, and 4 have the configurations S, R and R, respectively;
wherein xe2x80x94Xxe2x80x94Yxe2x80x94 is connected by a double bond or a single bond; wherein:
R2 is independently selected from the group consisting of Abu, Ala, Thr, Val, and norVal; R3 is Sar; R4 is MeLeu; R5 is Val; R6 is MeLeu; R7 is Ala; R8is D-Ala; R9 is MeLeu; R10 is MeLeu; and, R11 is Val or [D-MeVal].
Another preferred embodiment of this invention is a method of treating a neurological activity in an animal, comprising:
administering to an animal an effective amount of a non-immunosuppressive cyclosporin of formula IV: wherein:
R1 is MeBmt or dihydro MeBmt or represented by formula III; wherein positions 2, 3, and 4 have the configurations S, R and R, respectively;
wherein xe2x80x94Xxe2x80x94Yxe2x80x94 is connected by a double bond or a single bond; wherein: R2 is Abu or a fluorinated analog thereof; R3 is Sar, D-MeAla, or a fluorinated analog thereof; R4 is an N-methylated amino acid residue with a (C1-C9) straight or branched chain alkyl or alkenyl group;. these straight or branched alkyl or alkenyl groups may be substituted by cycloalkyl (C3-C8); R1 may also be (C3-C8) cycloalkyl or (C5-C7) cycloalkenyl;
the above alkyl, alkenyl, cycloalkyl or cycloalkenyl groups may be substituted with (C1-C4) alkyl or (C1-C4) alkenyl, or hydroxy, especially where R4 is MeLeu, MeVal, Me homo-Ala, or [Me-(xcex1-methyl)Thr]; R5 is Val or a fluorinated analog thereof; R6 is MeAla, MeAbu, or a fluorinated analog thereof; R7 is Ala or a fluorinated derivative thereof; R8 is (a) D-Ala or a fluorinated analog thereof; or (b) O-acyl-D-Ser or O-acyl-D-Thr wherein the acyl group is defined as R12 xe2x80x94COxe2x80x94 where R12 represents hydrogen, C1-6alkyl, phenyl or substituted phenyl of formula V wherein X1 and X2 independently are (a) C1-6alkyl;
(b) C1-6alkanoyl; (c) CH2OH; (d) halo; (e) C1-6alkoxy; (f) xe2x80x94NH2; (g) xe2x80x94NO2; (h) xe2x80x94COOH; (i) xe2x80x94COOC1-6alkyl; or (j) xe2x80x94H; R9 and R10 are independently MeLeu or a fluorinated analog thereof; and, R11 is MeVal or a fluorinated analog thereof.
Another preferred embodiment of this invention is a method of treating a neurological disorder in an animal, comprising: administering to an animal an effective amount of a cyclophilin inhibitor having an affinity for cyclophilin-type immunophilins to stimulate growth of damaged peripheral nerves or to promote neuronal regeneration, wherein the cyclophilin-type immunophilin exhibits rotamase activity and the cyclosporin derivative inhibits said rotamase activity of the immunophilin.
Another preferred embodiment of this invention is a method of treating a neurological disorder in an animal, comprising:
administering to an animal an effective amount of a cyclophilin inhibitor having an affinity for cyclophilin-type immunophilins in combination with an effective amount of a neurotrophic factor selected from the group consisting of neurotrophic growth factor, brain derived growth factor, glial derived growth factor, cilial neurotrophic factor, and neurotropin-3, to stimulate growth of damaged peripheral nerves or to promote neuronal regeneration, wherein the cyclophilin-type immunophilin exhibits rotamase activity and the cyclosporin derivative inhibits said rotamase activity of the immunophilin.
Another preferred embodiment of this invention is a method of stimulating growth of damaged peripheral nerves, comprising; administering to damaged peripheral nerves an effective amount of a cyclophilin inhibitor compound having an affinity for cyclophilin-type immunophilins to stimulate or promote growth of the damaged peripheral nerves, wherein the cyclophilin-type immunophilins exhibit rotamase activity and the cyclosporin derivative inhibits said rotamase activity of the immunophilin.
Another preferred embodiment of this invention is a method of stimulating growth of damaged peripheral nerves, comprising:
administering to damaged peripheral nerves an effective amount of an FKBP inhibitor compound having an affinity for cyclophilin-type immunophilins to stimulate growth of damaged peripheral nerves, wherein the cyclophilin-type immunophilin exhibit rotamase activity and the cyclosporin derivative inhibits said rotamase activity of the immunophilin.
Another preferred embodiment of this invention is a method for promoting neuronal regeneration and growth in animals, comprising:
administering to an animal an effective amount of a cyclophilin inhibitor compound having an affinity for cyclophilin-type immunophilins to promote neuronal regeneration, wherein the cyclophilin-type immunophilins exhibit rotamase activity and the cyclosporin derivative inhibits said rotamase activity of the immunophilin.
Yet another preferred embodiment of this invention is a method for preventing neurodegeneration in an animal, comprising:
administering to an animal an effective amount of a cyclophilin inhibitor having an affinity for cyclophilin-type immunophilins to prevent neurodegeneration, wherein the cyclophilin-type immunophilin exhibits rotamase activity and the cyclosporin derivative inhibits said rotamase activity of the immunophilin.